1. Field of the Invention
The invention relates to a heat exchanger, particularly to a heat exchanger which is best suited for use as a condenser or the like in air conditioners for the home or for vehicles.
2. Description of Prior Art
For example, previously the so-called serpentine type of heat exchangers have been used as heat exchangers for the purpose noted above. Forming the core of this serpentine type heat exchanger is a flat, perforated extruded tube a called harmonica tube which is bent into a serpentine shape with fin members interposed between the parallel portions formed between the bends of the tube. However, there have been a number of factors regarding these serpentine type of heat exchangers which limited the possibilities for efficiency improvement. One of which is that since the passage for the heat exchanging medium is formed by a single flat extruded tube, the area of passage cannot be ensured to be large. Also, because the extruded tube is bent into a serpentine shape, it is impossible to make the radius of curvature of the bends smaller than a certain limit, so the pitch of the tubes cannot be made small which limits the number of fin members that can be placed between the parallel portions of the tube and thus the efficiency of the fin members is poor.
Because of this, in recent years the so-called multi-flow type of heat exchangers have been appearing as replacements for the serpentine type of heat exchangers. Numerous flat, protruded tubes and fin members are alternately placed next to each other in this type of heat exchanger with both ends of the tubes connected to hollow headers. With this type of heat exchanger, since it is possible to freely select the tube pitch, it is possible to ensure that the cross-sectional area of the passage for the heat exchanging medium is large. Also, the number of fin members between the tubes can be increased making it possible for a small sized heat exchanger to perform with outstanding efficiency.
There are some cases in which these multi-flow types of heat exchanger, in order to let the heat exchanging medium flow through in a serpentine shaped pattern as occurs in the serpentine type of heat exchanger, partition members have been employed to split one or both of the headers' interiors into a plurality of partitioned chambers. By doing this, a serpentine shaped passage is formed by the tubes for the passage of the heat exchanging medium ( see Japanese Utility Model Publication Hei. 3-32944 and Utility Model Early Publication Hei. 2-92494).
FIG. 19 is an illustration of representative construction of these types of partition members. A slit shaped aperture 52 half the circumference of the header is formed along one edge of the header 51. The partition is constructed out of a roughly circular shaped partition plate 53 with a smaller diameter inner semicircular part 54 which conforms to the shape of the interior of the header 51 and a large diameter outer semicircular part 55 which conforms to the exterior surface of the header 51. Also, the inner semicircular part 54 of this partition plate 53 fits through the aperture 52 from the outside and is fitted into the inside of the header 51. Consequently, the inner semicircular part 54 contacts with the interior face of the header 51, while the outer semicircular part 55 is positioned so that exterior perimeter of the header 51 forms a single, continuous surface and is brazed or soldered to the header 51 and integrated therewith. Also indicated in the drawings are the tubes 56 and the corrugated fin members 57.
However, with regard to the relationship between the thickness of the partition plate 53 and the height of the slit shaped aperture 52, generally the partition plate 53 is designed such that its thickness is somewhat smaller than the height of the slit shaped aperture 52 so that errors of dimension or shape of these parts occurring during the manufacture or processing thereof will not make it difficult to insert the partition plate 53 into the slit shaped aperture 52. Consequently, in the above noted partition structure, between the time the partition plate 53 is fitted into the header 51 and brazed thereto, sometimes the partition plate 53 falls or slips out of place and is not brazed into its proper position.
Other examples proposed as structures to use partitions 61 to replace the partition plate discussed above are shown in FIGS. 20A and 20B. With this partition 61 a banded part 63 that conforms to the exterior surface of the header 51 is integrated into the outer semicircular part 62b of the partition plate 62 which corresponds to the aforementioned partition plate 53 so that arc-shaped lip-like ribs 63a jut out from the upper and lower ends of the partition plate 62. Also, this partition 61 allows the partition plate 62 to fit inside the header 51 through the slit shaped aperture 52, so that the inner semicircular part 62a contacts with the interior surface of the header 51 and both the lower and upper ribs 63a cover both sides of the aperture 52 exterior noted above and are brazed to the header 51 in that position to become integral therewith.
With regard to the partition 61 of this proposal, due to the brazing or soldering fillet between the exterior surface of the header 51 and the interior surface of the ribs 63a, the strength of the joint is improved. However, because the upper and lower ribs 63a are formed by a forging process, the productivity is poor and there are difficulties in creating ribs of sufficient height. Furthermore, another drawback is that, due to positioning defects in the partition, the efficiency of the heat exchanger is likely to deteriorate with this type of partition. Namely, when forming the slit shaped aperture 52 in the header 51 by notching or the like processing, sometimes deformations occur such as a turning up or bending of the edge of the slit shaped aperture 52. Because of the ribs 63a on the partition proposed above, it is very susceptible to the effect of these deformations. For example, even if one of the edges 52a of the aperture 52 is only slightly turned up as shown in FIG. 21, this causes the partition 61 to slant and a gap 64 to occur between the inner semicircular part 62a of the partition plate 62 and the interior of the header 51.